Generally, a vehicle seat is configured such that plural S-springs are fixed to a seat back frame. The S-springs elastically support an occupant. Therefore, the vehicle seat supports the back (shoulder blade) and the lumbar vertebra region of the occupant with the S-springs.
As this kind of vehicle seat, Japanese Unexamined Patent Application Publication No. 2001-253281 discloses a technology in which coupling members that couple S-springs with a seat back frame can be moved backward along slots formed in the seat back frame.
In addition, Japanese Unexamined Patent Application Publication No. 07-291005 discloses a technology of using coupling members, which extend backward, as a coupling member that couples S-springs with a seat back frame.